I have an electric oil pump and I thought would it be ok to suck the oil out and just top up with new. Or is it best to take the plate off ? Ta Marty
PS I ment rear diff

if you take the back plate of some have said they could not get a good seal on unless it is left for a couple of days for all the oil to come out ,I would suck it out, but do not swallow,LOL

No problem at all removing the rear diff cover on my '02, TD4 apart from breaking the seal (RTV sealant).
Far better to remove the cover and give the interior a look over for traces of metallic residue, followed with a good clean out using white spirit soaked rags.Make sure that the cover and the mating faces are clean and oil free then apply a bead of RTV silicone to the diff face and refit the cover-job done.
Wait an hour or so then fill the diff to the correct level-I didn't leave it for a couple of days for the RTV to set.
RTV is used for sump sealing on a lot of cars and the engine can be filled with oil and run an hour or so later....they don't keep the car in the workshop for a couple of days waiting for the sealant to "Go off" before putting the oil in !! The main thing to remember with RTV is that both faces are clean and oil free before application/reassembly

Thanks guys. I'll go with the oil pump idea. Main reason being I can only do the work at the caravan so may need to use the car quickly for EG need milk for a cuppa and you know that can't wait . Any recommendation on oil make. Again thanks for the replies.